12 g of powdered magnesium oxide reacts with nitric acid to form magnesium nitrate and water.
Calculate the mass of magnesium nitrate formed.
[Relative atomic mass of Mg = 24, N = 14,0 = 16] *

80.8 g

Explanation:

First, let's write a balanced equation of this reaction

MgO + 2HNO₃ → Mg(NO₃)₂ + H₂O

Now let's convert grams to moles

We gotta find the weight of MgO

24 + 16 = 40 g/mol

12/40 = 0.3 moles of MgO

We can use this to find out how much Magnesium Nitrate will be formed

0.3 x 1 MgO / 1 Mg(NO₃)₂ = 0.3 moles of Magnesium Nitrate formed

Convert moles to grams

Find the weight of Mg(NO₃)₂ but don't forget that 2 subscript acts as a multiplier of whatever is inside that parenthesis.

24 + 14 x 2 + 16 x 3 x 2 = 148 g/mol

148 x 0.3 = 80.8 g

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2